The matrix can be flat or cylindrical, and in both cases the speed of the surface to be printed and the speed of the matrix, along the line of contact between surface and matrix, must be strictly matched such as to avoid slippage resulting in smudging and poor print quality.
In order to achieve this result the prior art utilizes a chuck and a matrix connected by a mechanical link motion device, at least during the printing stage, which synchronizes the movements of the chuck and matrix.
Generally the matrix is located in a stationary printing station, while the chuck is one of a plurality of chucks supported radially in equidistant positions by a rotating platform known as a carousel and which advances in steps such as to successively present the chucks to the print station.
It is immediately evident that the need to provide mechanical link motion devices represents a laborious, complicated, and expensive solution, and this is not the only drawback in the prior art.
The main drawback is frequently the bulk of the chucks, which in solutions involving non-integral motor drives must be of significant axial lengths in order to leave space for the drive mechanisms.
It is consequently necessary to construct a carousel of suitably large diameter, in turn resulting in relatively high moments of inertia.
This type of printing machine generally exhibits an operating capacity of over four hundred cycles per minute, which means that the carousel must start and stop moving four hundred times per minute. The carousel is consequently subject to levels of acceleration that require very high material rigidity, robustness, and in particular the lowest possible inertia, which is not always possible when carousels are fitted to chucks of known type.
Italian patent application PR2003A000015 describes a printing machine, of screen printing type, wherein an object-bearing chuck is powered by a brushless motor, a shaft of which motor is mechanically connected via a transmission shaft to the object-bearing chuck.
This solution resolves some of the problems posed by exclusively mechanical-drive machines, but without resolving the problems of axial bulk or of the significant complexity resulting from a need to maintain both the transmission shaft and the object support chuck in motion.
Also unresolved are the problems deriving from a high moment of inertia of the rotating parts, which induces particularly high inertial forces as a consequence of the rotational velocity of the rotating parts and the extremely short drive and stop times required.